Evaluation of Physical Characteristics of Grain Dust
1981 Volume 11 Issue 2 Pages 19-27
Details
1981 Volume 11 Issue 2 Pages 19-27
This investigation was carried out to examine some of the physical characteristics of grain dust for the purpose of maintenance of clean environment and design of dust collection equipment, and to evaluate some parameters concerning morphological properties of grain dust. The results obtained were summarized as follows;
1) The density of grain dust had a tendency to increase with the decrease of particle diameter. The average value of the density was 1.55-1.65g/cm3, but the finer particle (less than 74μm) was larger than 1.7g/cm3. It was considered that the density might be concerned with composition of grain dust.
2) The specific surface area of the dust was not related to the particle diameter, and its constant value was estimated about 6000cm2/cm3. But the value obtained from particle size distribution curve was rather different from the above number. This seemed that the assumption of specific surface shape factor (φ) was not suitable for the calculation method.
3) From the comparison of the measured results on particle size distribution, liquid sedimentation method (hydrometer, and Andreasen-pipette method) had problems for measurement and analysis of particle size.
4) The average diameter of dust discharged from the rice drying facilities had a tendency to become smaller with the aduance of processes. The proportion of respirable dust in airborne particles was 9.1%, but in depositted dust, it was negligible.
5) The angle of contact of liquid to dust was approximately constant and independent of particle diameter. The value for water was about 90°. Hence, it was proved that wetting property of grain dust was awkward.
6) The value of φ for particle of grain hair (trichome) calculated as a model of hollow circular cone, was in good agreement with the measured value. Using this model, Some parameters concerning morphological properties of grain dust (trichome) made clear. Especially, the factor on the settling rate was considered to be a significance valae.
